RAO3(MO)k氧化物自然超晶格界面调控及其对热电传输性能优化的研究

超晶格界面对声子产生强烈散射从而大幅度降低热导率，已成为近年来热电材料设计的一个主要趋势。然而，超晶格界面一方面过滤低能电子提高Seebeck系数，另一方面则影响电子迁移率以至于电导率，因而其对热电性能的影响是复杂的，目前尚缺乏系统深入的探索研究。本项目拟以具有自然超晶格结构的多元氧化物体系为研究模型，如RAO3(MO)k 体系（R = Sc，In，Y 等；A = In，Fe，Ga，Al等；M = Mn，Co，Fe，Zn等；k为整数），通过改变化学成分和热处理工艺对超晶格的界面结构、化学组成、有序性及界面间距等因素进行调控，并在实验上测量观察相应的声子、电子输运性质，同时结合材料界面微观结构表征，及相关输运性质物理模型及第一性原理计算，进而从理论和实验上深度揭示超晶格界面诸多因素在传输性能上的影响机理。提出通过调控界面结构优化材料热电性能的有效方法，对研发高温热电材料具有重要的指导意义。

Nanostructure interfaces such as superlattices provide strong scatterings of phonons and therefore significantly reduce the thermal conductivity. Accordingly, nanostructure engineering has recently become an important approach to design thermoelectric materials. The superlattice interfaces, on one hand, increase Seebeck coefficient due to the filtering out of the low energy electrons, while may decrease electrical conductivity by affecting the charge carrier mobility. The net consequence of superlattices on the overall thermoelectric properties is rather complicated, and systematic and detailed study on this subject is still in need. In the present project, it is proposed that a natural superlattice oxide system is chosen as a model system, one example of which is the RAO3(MO)k homologous system（R = Sc，In，Y, etc.；A = In，Fe，Ga, Al, etc.；M = Mg，Mn，Co，Fe， Zn, etc.；k is an integer）. The superlattice interfaces have several factors that can be altered, such as the chemical composition and atomic structure, ordering and disordering, average interfacial spacing, etc. By characterizing the detailed interface structure and measuring the phonon and electrical transport properties, with the aid of thermal and semiconductor physics models and first-principle calculations, a deep insight into the correlation between the superlattice interfaces and thermoelectric transport properties can be made. The results will help us to understand how to tune the superlattice interfaces for optimizing the thermoelectric properties, which is a useful guide for discovering and designing novel high temperature thermoelectric materials.